1. Field of the Invention
The present invention relates to a method of manufacturing a magnetoresistive/inductive composite head and a magnetoresistive/inductive composite head, and particularly, to a method of manufacturing a magnetoresistive/inductive composite head and a magnetoresistive/inductive composite head which can form a recording head more precisely to a reading head.
2. Description of the Prior Art
Magnetoresistive heads using a magnetoresistive effect have attracted much public attention as a key device for promoting miniaturization of recent hard magnetic disk devices and increase of the memory capacity thereof, and of these heads, a magnetoresistive head using such a spin valve effect that the resistance change corresponds to the cosine between magnetization directions of two adjacent magnetic layers is being actively developed because it exhibits a large resistance change under application of a small signal magnetic field.
FIG. 1 shows the most practical structure of this head. As shown in FIG. 1, there has been known a magnetoresistive/inductive composite head including a magnetoresistive head and an inductive head.
The magnetoresistive head includes a pair of confronting magnetic shields 1 and 6 and magnetoresistive element 3 that is disposed in the gap between the magnetic shields 1 and 6. The magnetoresistive element 3 senses magnetic field occurring above a magnetic recording medium. The magnetic shields 1 and 6 and the magnetoresistive element 3 are disposed through reading magnetic gaps 2a and 2b. 
The inductive head includes the magnetic shield 6 serving as one magnetic pole (hereinafter, number 6 is indicated as a magnetic shield or a magnetic pole), another magnetic pole 8 disposed at the opposite side to the magnetoresistive element 3 with respect to the magnetic pole 6, a coil (not shown) for exciting the magnetic poles 6 and 8. The inductive head writes information on a magnetic recording medium by magnetic field occurring from writing magnetic gap 7 provided between the magnetic poles 6 and 8.
It has been known that a side fringe magnetic field that is not negligible occurs for writing information in such a composite type head as described above. The width of magnetic pole 6 which also serves as the magnetic shield is designed to be larger than the width of the magnetic pole 8 which inherently defines the writing width for information, and thus the magnetic flux leaks to the extra portion of the magnetic pole 6 which is beyond the magnetic pole 8 in width, resulting in occurrence of the side fringe magnetic field. The side fringe magnetic field thus occurring restricts the minimum writing width achievable. Therefore, in order to achieve a higher recording density, the composite type head must be designed so as to reduce the side fringe magnetic field at maximum. A method of reducing the side fringe magnetic field has been disclosed in Japanese Laid-open Patent Publication No. 7-262519.
According to the method disclosed in the publication, as shown in FIG. 2, the magnetic pole 6 is etched until a proper depth by an ion beam milling while the magnetic pole 8 is used as a mask so that the adjacent portion of the magnetic pole 6 to the writing gap 7 is cut so as to be identically with the magnetic pole 8 in width, thereby suppressing the side fringe magnetic field. However, with this method, the magnetic pole 8 is etched simultaneously with the etching process of the magnetic pole 6 as shown in FIG. 2, resulting in remarkable reduction of the film thickness of the magnetic pole 8. The reduction of the film thickness of the magnetic pole 8 may induce degradation of the writing characteristic due to a magnetic saturation phenomenon of the magnetic pole, etc. Accordingly, in order to finally obtain the magnetic pole 8 having a film thickness enough to a desired writing characteristic, the magnetic pole 8 is formed so as to have an extra film thickness by a flame plating method while the reduction amount of the film thickness is estimated in advance for the magnetic pole 8. That is, in order to achieve the above object, the frame height must be set to a large value. If the frame height is kept large, it would generally disturb reduction of the frame interval, that is, reduction of the writing width. In Japanese Laid-open Patent Publication No. 7-262519, the upper limit of the reduction of the writing width based on this method is equal to 2 xcexcm, and it is difficult to obtain a writing width less than 2 xcexcm.
Japanese Laid-open Patent Publication No. 5-143927 discloses a method of solving the above problem. According to this method, the writing width is specified by an ion beam etching from the confronting face side to the medium in a bar processing step after a wafer step is completed. In this method, a desired writing width can be achieved independently of the thickness of the magnetic pole 8, and thus there can be easily obtained such a structure that both of the reduction of the writing width and the reduction of the side fringe magnetic field can be achieved.
It has been increasingly required to strictly manage the relative positional relationship between the writing track position of the inductive head for performing an information writing operation and the reading track position of the magnetoresistive head for performing an information reading operation. This requirement is made to perform an ideal information reading/writing operation in a magnetic disk device, and the management of the positional relationship is more increasingly required to be performed with precision of 0.1, xcexcm particularly as the writing width is reduced to 1 xcexcm or less. With respect to this point, Japanese Laid-open Patent Publication No. 5-143927 teaches that a mark indicating the position of the reading track is located at an observable position in a magnetic pole processing step based on the ion beam etching. Furthermore, it discloses as a mark forming method a method of forming a predetermined mark in another step by using a photoresist mask having the same pattern as a photoresist mask used to determine the position of the reading track. However, in this method, the mark forming step and the reading track position determining step are not the same step, and thus a measure of dispersion remains in the alignment between both the photoresist masks even though the photoresist masks have the same pattern. Accordingly, even when the processing step of the writing pole is carried out on the basis of the mark, it cannot directly guarantee the positional relationship between the reading track and the writing track.
An object of the present invention is to provide a novel method of manufacturing a magnetoresistive/inductive composite head and a magnetoresistive/inductive composite head which can overcome the disadvantage of the prior art and reduce the side fringe magnetic field, and also can strictly manage the positional relationship between a writing track position and a reading track position particularly even under a narrow-width state that the writing width is equal to 1 xcexcm or less.
In order to achieve the above object, according to the present invention, there is provided a method of manufacturing a magnetoresistive/inductive composite head comprising a step of forming a magnetoresistive head which comprises a magnetoresistive element for sensing magnetic field occurring above a magnetic recording medium and an electrode portion for supplying sense current to the magnetoresistive element, the magnetoresistive element and the electrode portion being disposed between a pair of first and second magnetic shields disposed so as to confront each other through magnetic gaps; a step of forming an inductive head which comprises a first magnetic pole using the second magnetic shield as a magnetic pole, a second magnetic pole disposed at the opposite side to the magnetoresistive element with respect to the second magnetic shield and a coil for exciting the first magnetic pole and the second magnetic pole, wherein the writing of information is performed on the magnetic recording medium by magnetic field occurring from a writing magnetic gap provided between the first magnetic pole and the second magnetic pole; and a step of forming a recess potion for defining the width of each of the first magnetic pole and the second magnetic pole is formed on the surface of the second magnetic shield which confronts the magnetic recording medium on the basis of the end portion of the electrode portion.
Furthermore, according to the present invention, there is provided a magnetoresistive/inductive composite head comprising: a magnetoresistive head which comprises a magnetoresistive element for sensing magnetic field occurring above a magnetic recording medium and an electrode portion for supplying sense current to the magnetoresistive element, the magnetoresistive element and the electrode portion being disposed between a pair of first and second magnetic shields disposed so as to confront each other through magnetic gaps; and an inductive head which comprises a first magnetic pole using the second magnetic shield as a magnetic pole, a second magnetic pole disposed at the opposite side to the magnetoresistive element with respect to the second magnetic shield and a coil for exciting the first magnetic pole and the second magnetic pole, wherein the writing of information is performed on the magnetic recording medium by magnetic field occurring from a writing magnetic gap provided between the first magnetic pole and the second magnetic pole; and a recess potion for defining the width of each of the first magnetic pole and the second magnetic pole, the recess portion being formed on the face of the second magnetic shield which confronts the magnetic recording medium, wherein the end potion of the recess portion and the end portion of the electrode portion are in a predetermined positional relationship with each other.
The inventor of this application has earnestly studied and considered to perform the management of the positional relationship between the reading track position and the writing track position with precision of about 0.1 xcexcm in a magnetoresistive/inductive composite head having a narrow writing width of 1 xcexcm or less. As a result, the inventor has found that recognition of the reading track position can be dramatically enhanced by optimizing the material of the electrode potion for supplying the sense current to the magnetoresistive element, thereby enabling the processing step of the writing pole in which the reading track position is directly used as a reference. If any material of Au, Pt, W, Ta is selected as the material of the electrode portion, the intensity of an image recognition signal can be enhanced more greatly than when Cu or the like is selected as the material of the electrode. Furthermore, following the reduction of the reading gap in connection with the enhancement of the recording density, it is necessary to reduce the thickness of the electrode film to about 100 nm or less. However, it has been proved that more sufficient contrast can be obtained for such a thin-layer electrode by selecting one of Au, Pt, W, Ta as the electrode material than when Al2O3 film or Nixe2x80x94Fe film serving as a constituent material of the magnetoresistive/inductive composite head which is selected in terms of the processing.
Furthermore, as described in Japanese Laid-open Patent Publication No. 5-143927, the end portion of the electrode potion is generally designed in a taper shape, and thus in such a structure that the reading track position is defined at the end potion of the electrode, it is difficult to recognize the position of the reading track accurately. However, for this structure, the recognition of the reading track position can be dramatically enhanced by optimizing the forming step of the electrode portion, thereby enabling the processing of the writing magnetic pole while the reading track position is directly used as a reference.
FIG. 3 shows two processes for forming the electrode portion in a case where lift-off is carried out after a sputtering film forming step is carried out by using a photoresist mask. More Specifically, (b) of FIG. 3 shows a process when a normal radio-frequency (RF) sputtering method or magnetron sputtering method is used, and (a) of FIG. 3 shows a process when a high particle-directivity sputtering method, specifically, an ion beam sputtering method is used. It has been found that when the ion beam sputtering method is used, intrusion of sputtering particles to the lower side of photoresist mask 20 is suppressed, so that the shape of the end portion of electrode 5 can be accurately fixed, and also the recognition precision of the reading track position can be dramatically enhanced.